Spring actuated clamp

Abstract

A clamp for a posting board having a clamp arm and hinge which provides the desired clamping force to retain papers on the board, as desired, and also providing a continuous opening force when rotated beyond a fulcrum position defined by a pivoting extension tab of the hinge and a cantilevered leaf spring.

I claim: 
     
       1. An apparatus comprising: a posting board;   means defining a hinge provided along an edge of said board, said hinge means having a first knuckle means fixedly attached to said posting board and a second knuckle means including a lifter arm and an extension tab, said first and second knuckle means alternately engaging and rotationally pivoting about a hinge pin;   a flexible member cantilevered from the edge of said board;   a clamp arm attached to said lifter arm rotatable to a closed position in contact with said posting board, said extension tab contacting said member such that said clamp arm is biased toward said board when in said closed position, and said clamp arm being rotatable to an open position, said extension tab contacting said member to continually bias said clamp arm away from said board in said open position.   
     
     
       2. A clamp comprising: hinge means having a hinge pin and first and second sets of alternately engaging knuckles pivoting about said hinge pin;   a leaf spring cantilevered from a fixed reference surface having a lateral edge;   a tab attached to said first set of knuckles, said tab slideably contacting said leaf spring;   a clamp arm attached to and rotating with said first set of knuckles, said clamp arm being baised towards said fixed reference surface when said tab contacts said spring on one side of a fulcrum and said clamp being biased away from said fixed reference surface when said tab contacts said spring on the opposite side of said fulcrum.   
     
     
       3. A clamp as claimed in claim 2 wherein said second set of interengaging knuckles is integrally formed with said surface. 
     
     
       4. A clamp as claimed in claim 2 further comprising a series of projecting pins, said pins arranged linearly adjacent to said hinge means on said fixed reference surface. 
     
     
       5. A clamp as claimed in claim 4 wherein said clamp arm contacts said fixed reference surface on the opposite side of said pins from said hinge means when said clamp arm is biased towards said fixed surface. 
     
     
       6. A clamp as claimed in claim 5 wherein said pins project through apertures provided in said clamp arm when biased towards said fixed reference surface. 
     
     
       7. A clamp as claimed in claim 4 wherein said pins are provided with a butt which engages said leaf spring to position said spring in its cantilevered fashion. 
     
     
       8. A clamp as claimed in claim 2 wherein said first and second set of interengaging knuckles are formed by a series of intermittently spaced curls which wrap around said hinge pin in an alternating relationship. 
     
     
       9. A clamp as claimed in claim 8 wherein said tab is formed by a straightened curl of said first set of knuckles. 
     
     
       10. A clamp comprising: hinge means having a hinge pin and first and second sets of alternately engaging knuckles pivoting about said hinge pin; a body comprising a fixed reference surface having a lateral edge;   a leaf spring cantilevered from said lateral edge;   a tab attached to said first set of knuckles, and in contact with said leaf spring and said second set of knuckles being secured to said reference surface; and   a clamp attached to and rotating with said first set of knuckles, and which upon rotation thereof causes sliding contact between said tab and leaf spring so as to produce a reaction force which upon closure of the clamp towards the reference surface acts on movement of said tab past said fulcrum point to maintain the clamp in a closed position and which upon opening of the clamp acts to maintain the clamp in the open position upon movement of said tab past said fulcrum point.